Victims of cancer are often treated using chemotherapy and/or radiation therapy. Chemotherapy is the treatment of cancer using drugs that destroy cancer cells. Radiation therapy is the use of a type of energy, called ionizing radiation, to destroy cancer cells.
Brachytherapy is one type of radiation therapy used to treat cancer. Brachytherapy involves placing a small amount of radioactive material inside the body, near the cancer cells or tumor. Unlike external radiation treatment such as electron beam irradiation, brachytherapy enables a doctor to use a higher total dose of radiation to treat a small area in a shorter amount of time. Brachytherapy may be temporary or permanent. In temporary brachytherapy, radioactive material is placed near the cancer cells or tumor for a fixed period of time, and then withdrawn. In permanent brachytherapy, radioactive material in the form of “seeds” is permanently placed near the cancer cells or tumor. Although the seeds remain in the body permanently, the radiation levels of the seeds drop off over time.
Brachytherapy has been used in the treatment of numerous types of cancer, including cervical, breast, lung, head and neck, and prostate. For example, prostate cancer may be treated using Palladium-103 or Iodine-125 seeds. Depending on the prostate size and aggressiveness of the cancer, a health care provider can determine the number and positioning of the radioactive seeds needed to deliver a sufficient amount of radiation to kill the cancerous cells. In certain brachytherapy delivery systems, the requisite number of radioactive seeds, separated by bio-absorbable spacers, were loaded into brachytherapy needles and inserted into the prostate. Once the tip of the needle has been placed in its proper position, the needle is withdrawn, leaving a pattern of seeds and/or spacers.
Proper seed placement and seed retention at the implantation site influence the success or failure of a brachytherapy procedure. Certain seed implantation devices and methods often provide variable seed spacing and dosimetric patterns during and after implantation. Loose seeds, especially those that are extra-capsular (located outside the capsule of the prostate), tend to migrate within the patient, and as a result, may not provide radiation where needed and may sometimes cause damage to other radiation-sensitive areas of the body. In addition, the manual loading of seeds and connectors and/or spacers into the brachytherapy needle can be a laborious and time-consuming task.
As a result of the above, “stranded” seeds have been developed. Stranded seeds are connected together by connective material to form a strand. The seeds in a particular strand may be spaced apart by a predetermined interval to create a desired dosing level. By varying the spacing of seeds and the lengths of strands, strands can be formed with different desired dosing levels.
To facilitate the formation of strands of seeds, a brachytherapy seed deployment system has been disclosed in U.S. Pat. No. 6,010,446; and U.S. Pat. No. 6,969,344 (the contents of each of which are incorporated by reference as if fully set forth herein). The system comprises a basic unit of at least two seeds and a connector joining the seeds to maintain proper spacing between the seeds. Further alternating connectors and seeds may be connected to this basic unit to form a strand of seeds, each seed separated from adjacent seeds by the length of the connectors. The length of the connectors and the overall length of the strand may be varied to create a desired dosing level depending on patient needs. The connectors may be formed of solid rods of bioabsorbable material that degrade within 18-24 months after being inserted into the body. Suitable connectors include the SourceLink™ connectors sold by Bard Brachytherapy.
FIG. 1 illustrates three components of an exemplary brachytherapy seed deployment system designed to provide seed spacing in 0.5 cm increments. Reference character 100 designates an exemplary 5.5 mm standard connector, reference character 102 designates an exemplary 0.5 mm seed-to-seed connector, and reference character 104 designates an exemplary 5.0 mm extension connector. Used together, these components may form strands of certain lengths with certain seed spacings.
To apply these strands to the cancer cells or tumor, a hollow tube delivery device such as a needle, catheter or applicator may first be inserted into the affected area. Strands are then placed in the delivery device and either pushed into the proper location, or the delivery device is drawn out and the strands are seated in the proper location. Alternatively, the strands may first be placed into the delivery device prior to the insertion of the delivery device into the body. X-rays, ultrasound or CT scans may be among the tools used to ensure that the seeds in the strands are properly placed.
In temporary brachytherapy, the strands and the delivery device are inserted into the affected area and later removed from the body. In High-Dose Rate (HDR) brachytherapy, a specific high dose of radiation is delivered to the affected area through the delivery device for a short period of time controlled by a computer. This process may be repeated several times over the course of a single day. In Low-Dose Rate (LDR) brachytherapy, a lower dose of radiation is continuously delivered to the affected area through the delivery device over the course of hours or days.
In permanent brachytherapy, the strands may be left in the body after the delivery device is removed. The radioactivity of the seeds decays over time, and thereafter pose no threat to healthy tissues.
Cancer patients in need of brachytherapy may require certain treatment regimes, i.e. particular dosing levels that call for a discrete number of radiological seeds spaced apart by a predetermined distance in a strand of a particular length. For example, different dosing levels may be required depending on, e.g., the size of the patient, the nature of the tissue in which the seeds are to be implanted, and the type of cancer being treated. However, in conventional brachytherapy packaging services, little flexibility is provided, especially when on-site loading of strands is preferred by the health care provider. Conventional brachytherapy packaging services for on-site loading provide standard arrays of seeds to the health care provider regardless of the needs of the patient.
Thus, there is a need for a brachytherapy packaging system that is capable of delivering a particular number of strands of various lengths and predetermined seed spacings as requested by the health care provider. Such a packaging system would enable the health care provider to perform on-site loading and verification of dosing while avoid the expense of providing unnecessary and/or excessive quantities of strand configurations.